虚情假意
发表于 2025-3-30 09:46:30
Mesozoic to Tertiary basins — inland basinsntial thickness of Quaternary sediments in the Chad Basin..Cretaceous marine sedimentation was of shallow-water type, depositing limestones, sandstones and shales, with lithologies and fossils that indicate generally warm climatic conditions throughout. Maximum sediment thicknesses in the lullmedden and Chad Basins are of the order of 2000–3000 m.
Density
发表于 2025-3-30 15:24:50
The Permo-Triassic dolerites and carbonatiteshe newly discovered nepheline syenite-carbonatite complexes on the eastern margin of the West African craton, which are dated as Lower Permian (c. 265 Ma) and were emplaced in a well defined continental rift setting.
保存
发表于 2025-3-30 20:12:27
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PRISE
发表于 2025-3-30 22:47:03
Crustal development in West Africad orogenic events of deformation and regional metamorphism. The age of a particular geological province represents the time of the last of these events..Regional patterns of the West African Precambrian show some striking similarities, irrespective of age. In many areas a three-fold subdivision can
BARB
发表于 2025-3-31 01:50:38
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合适
发表于 2025-3-31 06:03:22
The Proterozoic of West Africaurnian thermo-tectonic event about 2 billion years ago. The supracrustals were probably deposited at least partly upon an older Liberian basement, but evidence for this is not conclusive..Both metavolcanic greenstone-type lithologies and metasediments occur among the Birimian sequences, the former p
巨头
发表于 2025-3-31 10:57:12
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卵石
发表于 2025-3-31 13:35:04
The Precambrian of West Africa — synthesis and reviewore than 2000 Ma of geological time.As there is good evidence that plate tectonics played a major part in the evolution of the Pan African domains, the resemblance to older terranes suggests that some form of plate tectonics has been active since the Archaean..The distribution of mineral deposits, h
GRIEF
发表于 2025-3-31 19:46:34
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BORE
发表于 2025-3-31 21:45:17
Infracambrian to Lower Palaeozoic basinsnset of sedimentation at around 1000 Ma ago, and products of a late Precambrian glaciation are recognised in both basins, marked by a distinctive association of tillite, limestone with barite, and chert..In the Volta Basin, the sediments can be correlated with rocks of the Togo belt, and the main ph